1. Field of the Invention
This invention relates to a heat exchanger apparatus for a vehicle, including an auxiliary radiator which is disposed on a cooling air upstream side of a refrigerant condenser in a refrigerating cycle to cool an exothermic component such as an inverter for controlling rotation of a driving motor.
2. Description of the Related Art
In a conventional refrigerating cycle of an automotive air conditioning apparatus, a refrigerant condenser is disposed on a cooling air upstream side of a radiator for cooling an automotive engine, and it is not necessary for a heat exchanger to be disposed on a cooling air upstream side of the refrigerant condenser.
Recently, however, a hybrid powered automotive, which runs using an engine and a motor together, has been developed to ease air pollution by exhaust gas from automotive engines. The hybrid powered automotive has an inverter for controlling rotation of the motor. The inverter has electronic components such as a power transistor, a calorific value from which is relatively large. Therefore, it is necessary for the hybrid powered automotive to use an auxiliary radiator for cooling the inverter. When the auxiliary radiator is cooling air type, it is desirable for the auxiliary radiator to be disposed at a position where outer air (cooling air) easily flows in to enhance the cooling effect of the radiator. As a result, in some cases, there arises necessity to disposed the auxiliary radiator on the cooling air upstream side of the refrigerant condenser.
In such an arrangement, high temperature air, which has abrosbed heat in the auxiliary radiator, flows into the refrigerant condenser to decrease a difference in temperature between the cooling air and refrigerant in the refrigerant condenser. This significantly loweres condensation capacity of the refrigerant condenser. Especially, in a case that the refrigerant condenser has a supercooling part for supercooling the refrigerant, the supercooling part can not sufficinetly exhibit the supercooling performance due to the rise of the cooling air temperature.